Changing Default Transaction Behavior

You can change default transaction behavior as follows:

To prevent updates to database content, explicitly start a transaction and specify that it is read only: START TRANSACTION READ ONLY (see START TRANSACTION). This setting is in effect for only this transaction. This starts an explicit transaction (see About Implicit and Explicit Transactions ) which will suspend the AUTOCOMMIT setting.

To change default autocommit behavior, specify SET AUTOCOMMIT OFF (See SET). When autocommit behavior is disabled and there is no START TRANSACTION statement, then execution of a statement implicitly starts a transaction. This transaction is open until you specify a COMMIT or ROLLBACK statement (See COMMIT, ROLLBACK). Autocommit remains disabled unless there is a SET AUTOCOMMIT ON statement or the connection closes.

To change the default transaction isolation level, specify SET ISOLATION LEVEL tx_iso_level. The new setting is in effect with the start of the next transaction and stays in effect unless the level is reset with another SET command or the connection closes. See Supported Transaction Isolation Levels for a description of each transaction isolation level that NuoDB supports.
Another way to set the default transaction isolation level is to specify the isolation connection property when you open a connection. For example:

When NuoDB executes a statement and there is not already an active transaction then NuoDB starts a transaction and applies the default transaction behaviors. The default transaction behaviors might be the original defaults or defaults that you have set or a mixture of both. An exception to this behavior is the START TRANSACTION statement, which lets you override default transaction behavior. See About Implicit and Explicit Transactions